Apparatus for treating wells



Oct. 24, 1944. J. .1. GREBE APPARATUS FOR TREATING WELLS Filed Aug. 28, 1940 5 Sheets-Sheet l INVENTOR i/oflnd Gree BY Mam 2 Zia T Z0 ATTORNEYS Oct. 24, 1944. J. J. GREBE APPARATUS FOR TREATING WELLS Filed Aug. 28, 1940 s Sheets-Shet 2 INVENTOR John J Grebe BY MV MZ ATTORNEYS Oct. 24, 1944. J GREBE 2,361,194

APPARATUS FOR TREATING WELLS Filed Aug. 28, 1940 3 sheets shee't- 3 59 JMW. 5

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INVENTOR ATTORNEYS fluid treating agent to be Patented Oct. 24, 1944 2,361,194 APPARATUS FOR TREATING WELLS John J. Grebe. Midland, Mich., assignor to The Dow Chemical Company, corporation of Michigan Midland, Mich, :1

Application August 2 8, 1940, Serial No. 354,505

creased in an amount directly proportional to the 7 Claims. The invention relates to apparatus for treating wells, such as oil, gas, brine, or water wells. It

more particularly, concerns a method and apparatus whereby a fluid treating agent may be simultaneously introduced into two or more Zones penetrated by the bore of a well while said zonesare sealed off or separated from one another in such a manner that the fluid treating agent in the well bore about to enter one zone is maintained out of contact with the fluid ntering the other zone.

The bore of a well oftentimes penetrates re than one producing section or zone, and it is usually desirable when treating such wells with a assured that some of the agent will be injected into each section. In some instances it is even desirable to closely control the amount of' agent that is injected into each zone. For example, in the treatment of more than one productive zone in calcareous earth or rock to bring about an increase in production by use of an agent such as acid, it is usually desirable that a method of treatment be provided to positively insure v that each zone will receive a proportionate quantity of the acid, for otherwise substantially all the acid may drain into the zone having the most porous structure with the resultthat little or no increase in production will be obtained from the zone or section having the smaller pore spaces or voids. It is further desir'able when treating such wells that the introduction of the fluid agent into each zone take place simultaneously in order to avoid the necessity of carrying out a separate treatment of each zone.

The term zone," used herein and in the appended claims, refers to separately defined strata as well as sections of a single formation or stratum.

It is, therefore, the principal object of the invention to provide apparatus whereby a fluid" treating agent may be simultaneously introduced into each of at least two zones penetrated by the bore of a well.

Another object of the invention is to provide an apparatus useful in connection with the simultaneous introduction of an acid or other treatting fluid into at least two zones penetrated by the bore of a well, which will automatically regulate any pro-selected ratio of rates of flow at any time during the treatment in such a manner that therate of flow to the zone which requires the application of the least pressure to force fluid thereinto at a previously selected rate is dediiference in pressure required.

Still another object is to provide an apparatus which maybe used for the simultaneous injection of a fluid agent into at least two zones and pointed out in the claims, the accompanying drawings and following description setting forth in detail apparatus for carrying out the invention, such mode illustrating, however, but one of several ways in which the invention may be put into operation.

In the accompanying drawings:

Fig. 1 is a fragmentary view of a well bore in vertical cross-section showing one embodiment of the invention.

Fig. 2 is a fragmentary sectional view of Fig. 1 showing that section of conduit 9 which includes the discharge orifice l2, and illustrates additional elements associated with the orifice which act to modify the action of said discharge orifice.

Fig. 3 is an elevational view of a well bore showing a modification of'the apparatus illustrated in. Fig. 1 wherein said apparatus is shown adapted for use in treating more than two zones Fig. 4 is a fragmentary cross-sectional view of a well bore showing another embodiment of the invention comprising a flow control element adapted for use in connection with the simultaneous introduction of a flu d treating agent mented in place by cement 4. The lower portion, '5 of the well bore penetrates productive stratum 6; an impervious stratum i, and ends in a second productive stratum 8. Attached to well tubing (not shown) conduit flextends into the well through the casing 2 and is shown provided with a threaded boss I0 at a point adjacent productive stratum 6. A bushing ll threadedly env the conduit 9 and the gages the boss l and is provided with an orifice l2 through which fluid may issue from the conduit 9 into the well bore. Attached to the conduit 9 at a point below boss i0 is a packing element I3 of conventional design, shown in a seated position so as to seal the annular space between well bore at a point intermediate the productive strata 6 and 8. A second conduit I4 is attached to the lower end of the packing element l3 and communicates with conduit B'through packing element l3. Engaging threaded boss IS in conduit I4 is a bushing l6, which is provided with an orifice l1 through which fluid may issue from the interior of the conduit 14 into the well bore at a point below the packing element l3 so as to contact productive stratum 8. The lower end of conduit I4 is provided with a cap member it of conventional design adapted to prevent egress of fluid from the lower end of the conduit I l. The portion of the well bore below the packing element l3, as well as the conduit I4, is shown filled with treating fluid I9, while the well bore exteriorly of the packing element above said element is also filled with treating fluid I! up to a point 3 adjacent the upper level of productive stratum 6. The remaining portion of the annular space between the well bore and conduit 9 is shown fllled with oil 20, which acts as a pressuring fluid and also controls the level to which the treating liquid rises in the well bore during a treatment. The treating fluid is also shown filling the interior of the conduit 9.

In the fragmentary sectional view shown in Fig.2, the orifice l2 of Fig. 1 is.shown equipped with a back pressure valve assembly. The housing 2| of the valve assembly is shown attached to conduit 9 adjacent orifice H, as by means of a weld. The valve assembly consists of a ported housing 2| having a well 23 in which valve stem 24 slides as pressure applied interiorly of the conduit 9 overcomes the pressure of spring 22 acting to force the valve into sealing relationship against-orifice I? provided in conduit 3.

In Fig. 3 the apparatus of- Fig. 1 is shown adapted for use in simultaneously introducing a treating fluid into more than two zones or strata. As shown, spaced productive strata 25, 26 and 21 are separated by impervious'strata 23 and 23. The productive strata or zones are shown sealed from each other by packing elements l3, such as shown in Fig. 1, seated against the impervious strata. Conduits 30, 3| and 32 attached 'to the pack ng elements l3 communicate with each other through the packing elements, and are provided wth ports 33, 34 and 33, respectively, which may be varied in size as desired and through which fluid' may enter the well bore and contact the productive zones while said zones or strata are separated from each other.

The fragmentary sectionalview shown in Fig. 4 illustrates a structure which may be employed according to the inven ion to simultaneously introduce'a treatin fluid into two zones while said zones are sealed from each other in such a mannet that the fluid entering one zone is maintained out of contact with the fluid entering the other zone. I to exercise control over the rateiof flow of fluid entering each zone or stratum so as to insure that the pro-selected ratio of rates of flow of the treating fluid will be automatically regulated, so as to decrease the rate of flow of fluid to that stratum or zone requiring the application of the Further, the apparatus is adapted- 33 is raised and rotated so lowest pressure to introduce fluid thereinto at the selected rate.

In addition, the apparatus may be employed in connection with accurately ascertainingthe productivity of each zone before or after treatment with a fluid agent has been accomplished, and to test the packing element as regards the effectiveness of the seal being obtained between the two zones.- As shown, well casing 2 extends into the well bore to a point above productive stratum 6 and is cemented on in the manner shown in Fig. 1. Conduit 36, adapted to be attached to the conventional well tubing (not shown) extends into the well and engages tubular member 31 in sliding sealing relation. The tubular member 31 is attached at its lower end to the packing element engageemnt with non-productive stratum I. A slot 33 extends transversely of the tubular member 31 and is provided at both ends and in the middle with depressions for locking engagement with a lug 40 attached to conduit 38. The slot and lug are so arranged that as the lug engages the depression at the extreme right of the slot, port 4| in conduit 38 registers with port 42 in the tubular member 31, while if the conduit that lug 40 engages the depression at the extreme left of the slot, port 4| in conduit 33 engages port 43 in tubular member 31. The lug 40 may also be caused to seat in the depression in the middle 01' the transverse slot 33, in which case port 4| in conduit 38 will not be in registry with either port 42 or 43, thus preventing flow of fluid to and from conduit 38 at a point above the packer 38. The conduit 30 extends into the central portion of the packing element 33 and ends in an inwardly projecting flange 44. The flange 44 acts as a seat for the body member 43 housing the control element, which is adapted to regulate the flow of fluid into the zones above and below the packer. The body 45 of the control element is held in position on the inwardly projecting flange 44 of the conduit by means of bolts 48 which engage a flange 41 of the body member. The body 45 oi the control element is in two sections secured to each other at flanges 43 by means of screws 43. The interior of the body of the control element is divided into two compartments by means or a diaphragm ill, which is secured to the body member'of the control element by screws 49 at flanges 43. The diaphragm'is of corrugated or bellows-like construction and is thus adapted to move laterally in either direction as pressure in one compartment builds up in excess of that in the other compartment. The diaphragm is provided on either face with centrally located tapered plug members ll, which are adapted to engage ports or oriflces 52 and I3 in the body member 1 so as to partly seal oi! or regulate the flow of fluid into either compartment as the diaphragm 30 moves back and forth. The tapered plug members ii are also adapted to engage springs 34 surrounding'the orifices 52 and 33 as the plug members are caused to move over and partially seal the orifices 32 and 33. The springs 54 compartment onthe right side of the diaphragm communicates with port 4| in conduit 33 by means 01' a tube 38, thus allowing fluid to escape from the interior or the control element into the stratum above the packer. The compartment on 33, which is shown in seated shown in registration with the left side of the diaphragm communicates through tube 56 with the space below the packer and allows the treating fluid to enter the formation below the packer. The lower end 'of conduit 36 is provided on its outer surface with lugs 51, which engage a longitudinal slot or narrow groove 56 in tubular member 59, and serve as a means whereby the packer may be seated or released by raising and lowering conduit 36. Below the packer body, tubular member 59 passes through a sleeve member 66, which it engages in' sliding sealing relation, and ends in an outwardly projecting fiang'e 6|. This flange engages a corresponding flange 62 of element 63. Element 63 ends in cap member 64, which bears against the bottom of the well bore. The tubular member 59 is provided with a port 65, which is port 66 in the sleeve member 60. The tubular member 59 is also provided with lug 61, which engages a slotted track in sleeve 60 so as to allow the tubular member 59 to rotate in sleeve 60, thus bringing port 65 into registration with the second port 68 insleeve 60. Port 66 is so located that as conduit is raised androtated through 90", or until lug 46 engages the depres-' sion centrally located in the transverse slot 39, port 65 then registers with port 68 in sleeve member 60. Flanges 6| and 62 are secured together by means of bolts 69 passing through slotted holes 16 in said flanges. This arrangement allows the conduit 36 and tubular member 59 to turn as a unit, and the ease of turning is facilitated by the fact that flange 6| can turn on flange 62 while element 63 remains stationary.

The method of the invention will be best understood from the following description wherein the apparatus illustrated in Fig. 1 is employed to carry out an acid treatment for the simultaneous injection of acid into two separately defined strata. With the apparatus assembled as shown, conduit 9 attached to the well tubing (not shown) is lowered into the well bore so as to position the packing element adjacent the impervious stratum' 1. The packer is then seated so as to separate productive stratum 6 from productive stratum 8, and a quantity of acid is introduced into the well through the well tubing in communication with the conduit 9. Pressure is then applied to the acid, as by pumping an additional quantity of acid into the well through the well tubing. At the same time oil is introduced into the annular space .exterior of the well tubing and the conduit 9 so as to control the level to which the acid solution can rise in the well bore as it escapes from the upper port or orifice l2} Acid is caused to discharge from orifice 12 as .well as from orifice l1 and enters both productive strata s multaneously.

' The orifices l2 and I I in bushings II and ii are conveniently chosen of such size that there will always be a pressure drop between the interior of conduit 5 and the well bore, as pressure is applied to cause the 'treatingfluid to discharge from the conduit. By varying the diameter of the orifices. more or less acid can be forced into a selected .zone. By selecting the orifices of such pressure can be maintained size that a higher interior-1y of the conduit than exteriorly thereof, and varying thev size of the orifice adjacent each zone, the amount of acid entering each zone is susceptible of control, and, at the same time. assurance is had that some acid is entering each zone if such arenot entirely impervious.

It is highly desirable to introduce the treatrate of flow at various pressures.

ing fluid at such a rate that a pressure drop is maintained across the orifices or restricted openings comparable to the pressure being employed to force the fluid into the zone or stratum having the highest resistance to the flow of the treating agent. The information required in order that a treatment he carried out in this manner may be obtained by testing the formations' before the actual treatment is carried out or, in some cases, it may be already recorded for the particular oil field or geographical location in question. Treating under such conditions insures that the apparatus will act to most effectively regulate the treating fluid. After the desired quantity of acid has been introduced, it

oil or the like into the well through said tubing.

5 The simultaneous introduction of the fluid agent above and below the packing element has the important advantage that the pressure applied'on one side of the. packing element to intrdduce the fluid agent acts to balance the pressure on the other side so that'the differential pressure across the packer is low, thus substantially eliminating any danger of a leak occurring around the packer or of the packer blowing out due to having a high pressure applied on but one side. After a suflicient amount of time has been allowed to elapse for the treating solution to react with the formation, it may be withdrawn from the well, as by a swabbing operation. The apparatus may then be withdrawn and the well put into production.

It s to be understood that the method is applicable .wherein it is desired to treat any desired number of spaced productive zones by sealing them from one another in the manner shown in Fig. 3 using a plurality each stratum and wherein one or more or fices of the desired size commun cate with each stratum.

It is also to be understood that the spring loaded back pressure valve assembly shown associated with the discharge orificeof the appae ratus illustrated in Fig. 2 may be employed in conjunction with the orifices, restricted openor the like, associated with the discharge ports or orifices. may be advantageously employed in some instances, as for example to compensate for differences in formation pressure existing in various zones so that an orifice may be selected to give the des red flow against the back pressure of the valve, thus eliminating the necessity of taking the formation pressure into consideration'when selecting anorifice to givea desired In this manher the rate of flow at various applie'dpressures is more nearly dependent upon exact orifice size.

The method of the invention may also be suitably carried out employing the apparatus illustrated in Fig. 4, which is adapted to automatically decrease the rate of flow of fluid,- e. g., acid, flowing into either stratum at any time during the treatment so as to direct a smaller rate of flow of acid to the stratum requiring the application of the least pressure to force the acid thereinto. The decreased rate of flow of-acid entering the stratum requiring the application of the least pressure to force fluid thereinto is.

directly proportional to the diminution in pressure required to force the fluid thereinto. It is usually highly desirable in carrying out an acid treatment that the rate of introduction be conof packers to separate trolled in the above manner because it oftentimes happens that one zone or stratum has a relatively low permeability to the flow of fluids and thus the desired fluid agent is prevented from gaining access to that stratum readily. In such cases it is therefore desirable that the rate of flow of the treating fluid be decreased to the one zone so that a relatively greater amount is directed into the more impervious stratum in order to bring about a relatively greater increase in permeability. The apparatus, assembled as shown in Fig. 4, is positioned in the well bore with ports ll and 42 above the seated packer and ports 85 and 88 below the packer in registry. A quantity of acid is then introduced into the well through the tubing (not shown), which is in communication with conduit 38. The acid flows downwardly into the body member 45 of the control element through orifices 52 and 53 provided therein. The fluid entering the left compartment escapes through tube 58 and thereafter through ports 85 and 88 and enters the lowermost zone or stratum 8. The fluid entering the right compartment discharges through tube 55 and ports 4! and 42 and enters the formation above the packer. If desired, a quantity of oil or other pressuring fluid (not shown) may be introduced into the annular space between the well casing and the conduit 38 to control the level to which the treating fluid rises in the well bore. If for any reason the fluid doesnot readily enter one formation, pressurebuilds up in the 'compartment of the control element communicating with the formation which the fluid is not entering readily and causes the diaphragm'SlI to move in a direction to relieve the p es thus actuating th plug members 5| so as to partially seal the orifice communicating with the compartment into which fluid is rapidly entering and discharging. This sealing action automatically continues as long as a higher pressure is needed to force the acid into the one stratum. Thereafter the plug members 5|, aided by spring 54, tend to assume a central location in the control element so as to allow acid to enter either compartment readily and flow therefrom into each stratum until for some reason the fluid does not readily enter one stratum. When this occurs, the plug members 5| again automatically curtail the flow of fluid into the stratum readily taking fluid so that as the treatment continues each stratum receives-a more desirable quantity of the treating agent. In the foregoing manner, the productive stratum which requires the application of the lowest pressure to force the fluid treating agent thereinto will be assured of having the rate of flow. of fluid agent thereto curtailed, which is desirable inasmuch as the highest rate of flow of the desired treating fluid should generally be to the stratum or strata having the highest resistance to the flow of fluids thereinto.

It will be readily apparent that the volume of the treating agent entering either stratum may be further controlled to some extent by selecting larger or smaller oriflces. For example, theextent or thickness of each stratum is usually known prior to a treatment, and in such cases oriflces may be selected which will allow the fluid treating agentto flow therethrough in an amount roughly proportional to the extent or thickness of the formation.

- After the desired amount of acid has been introduced into each stratum it may be desirable to ascertain the increase in the productivity of each stratum and the apparatus illustrated in Fig. 4 is adapted for use in making such a meas-' urement. If it is first desired to test the productivity of lower stratum 8, while the flow of fluid from stratum 8 is sealed oil, conduit 38 is lifted so that lug 40 is free to move in the transverse slot 39 in conduit 31. Conduit 38 is rotated through 90 or until the lug 48 engages the depression centrally located in the transverse slot 39. At this time port 88 in the tubular member 58 will be in registry with port 88 in element 80, allowing fluid to flow into the interior of the assembly from stratum 8. At this time port 4| in conduit 38 will be sealed against tubular member 31, preventing fluid from flowing into the interior of the assembly from productive stratum 8. The well may be allowed to flow, and since the upper formation 8 is sealed so that fluid cannot enter conduit 38, an accurate production test on stratum 8 can be made. Thereafter a. production test of stratum 8 is made while fluid entry into cOnduit 59 from stratum 8 is prevented. This is accomplished by raising conduit 38 slightly so that lug 40 disengages the depression in the center of the transverse slot 39. The conduit 38 is then rotated so that the lug 48 engages the depression at the extreme left of transverse slot 39, at which time port 4| will register with port 43 in the tubular member 31, while port below the packing element will be sealed against the sleeve member 80. Thereafter the well may be allowed to flow and thus the productivity of stratum 8 is ascertained while fluid entry from stratum 8 is prevented. In the same manner the apparatus may be employed to test the flow of fluids before a treatment has been carried out. Similarly the effectiveness of the seal produced by the packer may be tested by attempting to circulate a fluid such as oil around the packer. This may be accomplished by pumping the oil or the like into the well through conduit 38 and into the well bore below the packer while conduit 38 is not in communication with the well bore above the packer, or by sealing of! the conduit effective seal.

The method will be found to have most general use in connection with an acid treatment wherein a solution of hydrochloric or other acid is introduced into the formation to bring about solution of the earth or rock formation and thus an increase in size of the flow channels through which the desired mineral fluid flows to the well. In such treatments it will usually be found preferable to employ an aqueous solution of hydro chloric acid of from 5 to 25 percent concentration. If desired, such an acid may. be inhibited against corrosive. attack upon iron or steel in the manner taught in U. S. Patent No. 1,877,504.

Although the method has been described with particular reference to an acid treatment, it is to be understood that any fluid treating agent may be introduced in accordance with the method of the invention. Examples of such treating agents are paraffin solvents,- liquid sealing agents, and

more satisfactory treatment than is the case if the conventional method is employed wherein the bore hole is merely filled with the treating fluid and pressure is applied thereto whereby the treating iiiid is directed indiscriminately to each stratum.

1. In a well treating 'device for the simultaneous introduction of a fluid agent into at least two zones penetrated by the bore of a well, the combination of a conduit having spaced openings therein, sealing means surrounding said conduit adapted to seal the annular space between the conduit and the well bore at a point between the openings, a control element sealed in said conduit having ports for the entry of fluid into the interior thereof and fluid exit ports communicating respectivelywith the spaced openings above and below the sealing means, and a movable member dividing and sealing the interior of the control element into two compartments so that a fluid entry port and a fluid exit port communicate with each compartment, said movable member being adaptedto engage the fluid entry ports in partial sealing relationship as the movable member is caused to move by pressure building up in one compartment in excess of that in the other compartment.

2. In a well treating device for the simultaneous injection of a fluid agent into at least two zones penetrated by the bore of a well, the com-,- bination including a conduit having spaced openings therein, sealing means surrounding said conduit adapted to seal the annular space between the conduit and the well bore at a point between thesaid openings, a control element sealed in said conduit having ports for entry of fluid into the interior thereof, and fluid exit ports communicating respectively with the spaced openings above and below the sealing means, a movable diaphragm member dividing the interior of the control element intov two compartments-so that a fluid entry port and a fluid exit port communicate with each compartment, and a plug member carried'by the movable diaphragm adapted to engage the fluid entry ports in partial sealing relationship as the diaphragm is caused to move laterally by pressure building up in one compartment in excess of that in the other compartment.

3. The apparatus of claim 2 wherein a spring loaded back pressure valve is associated with one of the fluid exit ports.

4. In a well treating device for the simultaneousinjectlon of a fluid agent into at least two zones penetrated by the bore of a well, the combination of a conduit having spaced openings therein, sealing means surrounding said conduit adapted to seal the annular space between the conduit'and the well bore at a point between said openings, 9. control element sealed in said conduit having ports for entry of fluid into the interior thereof and fluid exit ports communicating respectively with the spaced openings above and below the sealing means, a movable member di-- viding the interior or the control element into two compartments so that a fluid entry port and fluid exit port communicate with each compartment, a 'plug I member carried by the movable member adapted to engage the fluid entry ports in partial sealing relationship as the movable member is caused to move laterally by pressure building up in one compartment in excess of that in the other compartment, and springs associated with the fluid entry ports adapted to engage the plug member as itmoves laterally to prevent complete sealing of the fluid entry ports.

5. In a well treating device for the simultaneous injection of fluid agent into at least two zones penetrated bytthe bore of a well, the combination including aconduit having spaced openings therein, sealing means surrounding said conduit adapted to seal the annular space between the conduit and the well bore at a point between the openings, a control element sealed in said conduit having ports for entry of fluid into the interior thereof and fluid exit ports communicating respectively with the spaced openings above and below the sealing means, said fluid entry ports having a diameter which is proportional to the thickness of the zones with which they communicate, a movable diaphragm member dividing the interior. of the control element into two compartments so that a fluid entry port and a fluid exit port communicate with each compartment, and a plug member carried by the movable diaphragm adapted toengage the fluid entry ports in partial sealing relationship as the diaphragm is caused to move in the compartment.

6. In a well treating device for the simultaneous introduction of a fluid agent into at least two zones penetrated by the bore of a well, the combination of a conduit having spaced openings therein, sealing means surrounding said conduit adapted to seal the annular space between the conduit and the well here at a point between the openings, a control element comprising a housing sealed in said conduit and having ports ,ior the entry of fluid from within the conduit into the interior thereof and fluid exit ports each communicating with one of the entry ports andwith one of the spaced openings and mechanism within said housing whereby the fluid flowing to one'of said exit ports operates to control the flow of fluid through the other.

7. In a well treating device for the simultaneous introduction of a fluid agent into at least two zones penetrated by the bore of a well, the combination of a conduit having spaced openings therein, sealing means surrounding said conduit adapted to seal the annular space between the conduit and the well bore at a point between the openings, a control element sealed in said conduit having a movable member therein dividing the interior thereof into two compartments each having an entry port to admit fluid from the conduit and an exit port communicating with one of the above mentioned spaced openings, said movable side.

' JOHN J. GREBE. 

